Feedthrough device and signal conductor path arrangement

ABSTRACT

Feedthrough device ( 50; 150 ), for forming a hermetic seal around signal conductors in a signal conductor group ( 60; 160 ) with a group width. The device comprises a slotted member ( 52; 152 ) and a base ( 62; 162 ). The base defines a through hole ( 65 ) that extends entirely through the base along a feedthrough direction (X), and is adapted to accommodate the slotted member. The slotted member defines first and second surfaces ( 53, 54; 153, 154 ) on opposite sides associated with the feedthrough direction, and a side surface ( 55, 56; 155, 156 ) facing transverse to the feedthrough direction. The slotted member comprises a slot ( 58; 158 ), which extends along the feedthrough direction through the slotted member, and opens into the first and second surfaces and into a longitudinal opening ( 59; 159 ) along the side surface. The slot extends transversely into the slotted member up to a slot depth at least equal to the signal conductor group width.

TECHNICAL FIELD

The invention relates to a feedthrough device, to a signal conductorpath arrangement including at least one such feedthrough device, and toa vacuum chamber and a processing system including such signal conductorpath arrangement, wherein the signal conductors encompass for exampleoptical fibers and electrical conductors, among which electricalconductors arranged in a printed circuit board.

BACKGROUND ART

In semiconductor industry, including various types of semiconductorprocessing and manufacturing devices, an ever-increasing desire existsto manufacture smaller structures with high accuracy and reliability.Lithography is often a critical part of such manufacturing processes.During lithography exposure or other types of processing, the target(e.g. a semiconductor wafer) may need to be situated in a high vacuumenvironment that is hermetically sealed from the surroundings (e.g. fromatmospheric conditions), to reduce the probability of contamination.

In the particular case where such vacuum environment is applied foroperating a mask-less lithography system, charged particle beamlets maybe used to transfer a pattern onto the target. The beamlets may beindividually controllable to obtain the desired pattern. To becommercially viable, mask-less lithography systems need to meetchallenging demands for wafer throughput and error margins. A higherthroughput may be obtained by using more beamlets. The handling of agreater number of beamlets calls for more sophisticated control devicesand circuitry, without compromising the necessary vacuum conditions orsignificantly increasing the required fab space (i.e. the area coveredby the processing unit). The task of arranging more process controldevices and/or circuitry in a decreasing available volume whilemaintaining hermetic seals between various parts of the lithographysystem becomes more and more challenging.

For the control of the lithography systems, including control of a largenumber of beamlets for exposing the target as well as various othercontrol devices and circuitry, various types of signals, encompassingpower supply signals, various electrical signals, and/or opticalsignals, have to be transmitted or passed through the boundary of thevacuum environment.

In relation to the technological subject of feedthrough of eithersignals or electric power from one environment or compartment toanother, the publication “Hermetic Sealing with Epoxy” of W. D. Wood andW. L. Wood, Mechanical Engineering Vol. 112, March 1990, p. 46(http://www.pavetechnologyco.com/pdf/hemetic_pdf), describes this as along standing basic and generic technology, using glass or ceramicfilled metal housings. The publication also describes a majordevelopment in this technology by the application of epoxy based sealingin bulk heads and other type of signal or power feedthrough from theearly 1980's. The publication indicates that epoxy sealing provides goodvacuum sealing in combination with various materials used in and/oraround electrical conductors, including aluminum as widely used forcreating vacuum environments, and copper as widely used for conveyingelectric signals, as well as various insulating materials. It is furtherindicated that epoxy seals comply with cleanliness requirements makingthem suitable for use in vacuum wafer-handling systems.

From the teaching of the article of Wood and Wood it may hence beconcluded that epoxy sealing can be expected to be applicable also forhermetically sealing printed circuit boards (PCB) in an electricalfeedthrough.

An example of such known type of PCB feedthrough using a bulkhead incombination with an O-ring is provided by patent document U.S. Pat. No.6,305,975B1, which describes the feed through of a PCB permanentlyencapsulated in an epoxy based bulkhead. The PCB with bulkhead may inprinciple be formed as the cover for a cylindrically shaped opening of alow pressure chamber, and is at its perimeter sealed to the openingusing an O-ring type of vacuum seal.

Patent document U.S. Pat. No. 7,164,142B2 shows examples of vacuumfeedthrough including the known face type sealing. A structure for anelectrical feedthrough is described, utilizing a sheet of insulatingmaterial including at least one embedded layer of conductive tracks,where the sheet face is sealed to the vacuum wall using a fillet ofsealing material. PCB is indicated to form an example of such insulatingmaterial comprising a plurality of conductive tracks.

While the latter mentioned feedthrough of U.S. Pat. No. 7,164,142B2merely seems to provide for permanent sealing of a PCB feedthrough, theolder, in 2001 published patent US630597B1 forms a more versatiledesign, providing a releasable PCB feedthrough connector.

Patent document U.S. Pat. No. 8,242,467B2, assigned to the currentapplicant, discloses a multi-beamlet lithography system. This systemcomprises a beamlet blanker (or modulator) for selectively allowing ordenying individual beamlets passage to the target, based on patterndata. The beamlet blanker is arranged near the target in a vacuumchamber, but controlled by a control unit that is located outside thevacuum chamber. The lithography system includes an optic system with anarray of optical fibers for transmitting modulated light signals withthe pattern data from the control unit to light sensitive blankingactuators on the beamlet blanker. The fibers are routed via an openingin a feedthrough device through a wall of the vacuum chamber. Vacuumcompatible sealing material is used to provide an airtight sealing forthe fibers in the opening. U.S. Pat. No. 8,242,467B2 presents littledetails in relation to the structure of the feedthrough device.

Patent document US2016/0787599A1 describes fiber alignment assembliesfor hermetically feeding optical fibers through a housing of anopto-electronic module. One such assembly includes a ferrule, with twoadjoined ferrule portions. One ferrule portion has a surface with fouralignment grooves, which accommodate end sections of optical fibers. Thesecond ferrule portion covers the surface and the alignment grooves ofthe first ferrule portion, when the ferrule portions are mated togetherto form the ferrule. Sealant material, such as glass solder, may then befed into the ferrule, through an aperture in one of the ferruleportions. Vacuum is applied to a pocket in the ferrule, to draw theglass solder through clearances between the optical fibers and grooves,to form a hermetic seal. The hermetic assemblies from US2016/0787599A1are primarily suitable for feeding through relatively small numbers ofindividual optical fibers.

It would be desirable to provide a feedthrough device that is suitablefor routing a large number of signal conductors, such as optical fibers(i.e. several tens or hundreds) or electrical conductors, for exampleprovided in printed circuit boards, in an ordered and hermeticallysealed manner through a structure that separates two regions withdifferent ambient conditions.

It is also desirable to provide vacuum feedthrough devices which allowfor reliability, versatility and repeatability in a contemporaryindustrial design.

SUMMARY OF INVENTION

Therefore, according to a first aspect of the invention, there isprovided a feedthrough device for forming a hermetic seal around aplurality of signal conductors. The signal conductors extend along eachother to form a signal conductor group with a group width. Thefeedthrough device comprises a slotted member and a base. The slottedmember defines, in fact is delimited by, a first surface that facespredominantly towards a feedthrough direction, a second surface thatfaces predominantly opposite to the feedthrough direction, and a sidesurface that interconnects the first and second surfaces and facesoutwards in a direction non-parallel to the feedthrough direction, forexample at an oblique angle or transverse to the feedthrough direction.The base defines a hole that extends entirely through the base along thefeedthrough direction, this hole being adapted to accommodate theslotted member. The base defines an inner surface that directlysurrounds the hole. The base is adapted to accommodate at least part ofthe slotted member inside the hole, in such a way that the inner surfacecovers at least part of the side surface and the longitudinal opening ofthe slotted member. The slotted member includes at least one slot, whichextends along the feedthrough direction through the slotted member, andopens into the first and second surfaces, to allow the signal conductorgroup to pass from the first surface through the slotted member to thesecond surface. The slot further opens into a longitudinal opening,which extends along the side surface. The slot extends from the sidesurface along a depth direction transverse to the feedthrough directionup to a slot depth into the slotted member. This slot depth is equal toor larger than the group width.

The signal conductors may comprise any type of substance or body capableof transmitting energy and/or information, generally in the form oflight or electricity. Typical examples of signal conductors encompassedby the present invention are optical fibers, for transmitting lightsignals, and electrical conductors, for transmitting electrical signals,for example in the form of printed circuit boards (PCB's) comprising aplurality of electrical conductors.

The individual signal conductors forming the signal conductor group arenot necessarily arranged abutting one another, but can be arranged at adistance from one another. The signal conductors may be arranged in amaterial or substance, and/or arranged on a surface, such as to bespaced from one another. The group width is defined as the width of thegroup of signal conductors, where the signal conductors are arrangedabutting one another or at a distance from one another. When the signalconductors are provided as electrical conductors in a PCB, the groupwidth is defined by the width of the PCB.

A hermetic seal is an airtight seal, in particular when subject to largepressure differences such as in vacuum applications. The feedthroughdevice in particular forms a vacuum feedthrough device, suitable forhigh vacuum applications.

The signal conductors extend co-directionally and alongside each other,to form the signal conductor group. The signal conductor group ispreferably substantially flat. The signal conductors in the group maydirectly abut, or may have some spacing in between. When the signalconductors comprise optical fibers, the optical fiber groups may bearranged in the form of ribbons. When the signal conductors compriseelectrical conductors, these may form part of a printed circuit board.

The slot forms a narrow groove that extends from the longitudinalopening at the side surface, inwards into the slotted member, and allowsa longitudinal portion of the associated signal conductor group to beeasily and reliably inserted into the slotted member duringmanufacturing of a signal conductor path arrangement. The transverseextent of the slot into the slotted member allows the signal conductorgroup, which preferably is flat, to be inserted sideways into theslotted member, while leaving a large part of the periphery of theslotted member available for other slots and signal conductor groups.The slot depth is at least equal to the group width, but may be largerin order to provide additional slot space. When the signal conductorscomprise an optical fiber group, this excess slot space may for examplebe used to insert a retaining wire or strip next to the fiber group intothe slot, to block the longitudinal opening and hold the fiber groupinside the slot. The proposed arrangement of flat signal conductorgroups and slots allows a large number of signal conductors (i.e. in theorder of tens or hundreds or more) to be routed through the feedthroughdevice in a hermetically sealed and well-ordered manner.

The slotted member and base have thicknesses (or depths) defined alongthe feedthrough direction, and cross-sectional areas defined in planestransverse to the feedthrough direction. These dimensions may be adaptedto meet specific requirements in relation to differential pressures andstructural robustness. For example, the thicknesses of the slottedmember and base may be in a range of 5 millimeters to 40 millimeters,and the cross-sectional area of the slotted member may in a range of 100square millimeters to 1500 square millimeters.

Preferably, the slot has a predominantly rectangular shape, whichextends transversely from the longitudinal opening inwards into theslotted member, along a linear trajectory with the slot depth. The slotmay have a slot width in a width direction transverse to both thefeedthrough direction and the depth direction, which is smaller than theslot depth along the entire depth extent of the slot. This slot widthmay remain constant along the entire depth extent of the slot. The slotmay extend into the slotted member in a direction perpendicular to alocal portion of the side surface that borders on the longitudinalopening.

The arrangement with a slotted member accommodated in and surrounded bya base, can be accurately aligned and is robust. The inner surface ofthe base covers the longitudinal opening(s) of the slot(s) in theassembled state of the device, and ensures that signal conductor groupsare properly retained within their slot, before a sealing body isapplied to the arrangement.

According to an embodiment, the first surface of the slotted member isrecessed along the feedthrough direction relative to a surface of thebase that directly surrounds the hole, when the slotted member isaccommodated in the hole. In this embodiment the first surface of theslotted member is recessed to such an extent that at least the firstsurface of the slotted member and the inner surface of the base form areceptacle in which a sealing body can be accommodated.

The resulting receptacle forms a container that allows a sealing body tobe formed, by pouring liquid sealant material into the receptacle, andletting this liquid sealant material cure. Gravitational pull may beexploited, to let the liquid sealant material distribute itself acrossthe first surface of the slotted member and cover part of the slot(s)where the signal conductor group(s) exits the slot (s), to enveloppart(s) of the signal conductor group(s) and provide a hermetic barrier.The liquid sealant material may thereby be drawn into the slot(s),possibly assisted by capillary action, so that the cured sealing bodywill extend along at least part of the slot(s) in the feedthroughdirection. Space between the inner wall of a respective slot and thelongitudinal portion of the associated signal conductor group will thusalso become occupied by the sealing body, to yield an improved sealingeffect. Such a sealing body covers the first surface of the slottedmember and at least the part of the slot where a signal conductor groupexits the slot, to envelop the signal conductor group and form ahermetic barrier between first and second regions that are outside theslotted member and border on the first and second surfaces of theslotted member, respectively.

This liquid sealant material may for example be a glue, adhesive orresin, for example an epoxy-based glue, adhesive or resin, that adheresto the first surface of the slotted member and to the inner surface ofthe base adjacent to the liquid sealant material. The viscosity of theuncured glue preferably is sufficiently low to allow the uncured glue toenter the slot(s) and locally envelop a portion of the signal conductorgroup, for example in the form of an optical fiber group or a printedcircuit board, inside this slot, but also sufficiently high to preventthe liquid sealant material from flowing through the entire slot and viathe second surface out of the slotted member. In the case that a maximumdistance between an inner wall of a slot and an outer surface of asignal conductor within the group inside this slot is always below 0.5mm, a viscosity in a range of 20 Pa·s to 50 Pa·s may be suitable.

According to embodiments, the side surface of the slotted member has across-sectional shape that resembles a stadium or a rounded rectangle.The inner surface of the base around the through hole may have a similarcross-sectional shape, which is adapted to accommodate the slottedmember in a form-fitting manner.

A stadium and a rounded rectangle have linear edges and rounded edges,but omit sharp corners. Several manufacturing-related advantages may beobtained by forming the lateral outer and inner surfaces of the slottedmember and base with similar cross-sectional shapes of theabove-mentioned types. The finite rotational symmetry of such shapesfacilitates alignment between the base and the slotted member. Thelinear edges provide regions in which slots are more easily formed in amutually parallel and/or regularly distributed manner, which in turnfacilitates insertion of fiber groups. Furthermore, the rounded edgespromote equal distribution of liquid sealant material along the firstsurface and slot(s).

According to embodiments, the side surface of the slotted member definesa flat surface portion that extends in a translationally symmetricmanner along a direction perpendicular to the feedthrough direction. Thelongitudinal opening may be located at this flat surface portion, andthe at least one slot may extend perpendicular to the flat surfaceportion into the slotted member.

Forming of the slot(s) and insertion of the signal conductor group(s) inthis slot(s) is facilitated by forming the slotted member with a flatside surface portion and with one or more slots that extendperpendicularly to this flat surface portion into the slotted member.

According to embodiments, the side surface of the slotted member definesa first side surface segment, which is inwardly tapered towards an axisalong the feedthrough direction. In addition, the inner surface of thebase may be inwardly tapered congruent to the first side surfacesegment.

This axis corresponds with coinciding central axes of the slotted memberand the hole in the base. The inwards tapering implies that the firstside surface segment is locally tilted to face partially laterallyoutwards and partially towards the feedthrough direction. Similarly, theinner surface of the base may be locally tilted to face partiallyinwards and partially towards the feedthrough direction. Due to thetapering, the slotted member and the hole in the base jointly decreasein size as a function of position along the feedthrough direction. Thisensures that the slotted member will automatically find an optimalfitting position in the hole, after which it will be prevented frommoving further though the base. Any excess pressure exerted on the firstsurface of the slotted member will keep the slotted member fixed insidethe base. This is advantageous in operational setting wherein theoutside pressure exceeds the pressure inside the vacuum chamber. Theinwards tapering may extend along at least part of the transverse outerperiphery of the slotted member and at least part of the transverseinner periphery of the base. In particular, the inwards tapering mayextend along the entire outer and inner peripheries of the slottedmember and base, respectively. The inwards peripheral tapering mayextend along at least part of the thickness of the slotted member andthe base, viewed along the feedthrough direction.

According to further embodiments, the side surface of the slotted memberincludes a second side surface segment. This second side surface segmentis inwardly tapered, chamfered, or filleted towards the axis, but in anopposite manner with respect to the first side surface segment.Alternatively or in addition, the inner surface of the base may includean inner surface segment that is outwardly tapered, chamfered, orfilleted away from the axis, such that the second side surface segmentand/or inner surface segment define an inwards peripheral recess. Thisinwards peripheral recess directly borders on the at least onelongitudinal opening in the slotted member, and is adapted toaccommodate a portion of the sealing body.

The inward peripheral recess, defined by the tapered/chamfered/filletedsecond side surface segment of the slotted member and/or thetapered/chamfered/filleted inner surface of the base, directly surroundsthe first surface of the slotted member and borders on the longitudinalopening(s) of the slot(s). The peripheral recess allows liquid sealantmaterial to partly cover and be drawn into the longitudinal recess(es),in order to embed longitudinal portion(s) of the signal conductorgroup(s) inside the slot(s) within sealant material, and improve thehermetic seal provided by the feedthrough device. The inwards/outwardstaper/chamfer/fillet may extend along at least part of the transverseouter periphery of the slotted member and at least part of thetransverse inner periphery of the base. The tapered/chamfered/filletedregions may for example cover at least those surface regions where slotsreside, or may alternatively extend around the entire transverseperipheries. The height of the taper/chamfer/fillet along thefeedthrough direction is preferably limited to the region near the firstsurface of the slotted member.

According to embodiments, the slotted member and the base form rigidbodies that consist essentially of one or more solid materials.

The solid materials for the slotted member and the base preferably haveno or negligible viscoelastic properties, at least in the typicaloperational temperatures and typical differential pressures between thefirst and second regions associated with the two hermetically sealedsides of the feedthrough device. The geometries of these bodies thusremain intact, even under varying pressure and temperature conditions.The solid materials are preferably selected from the group of metals ormetal alloys that are solid at room temperature, and have low outgassingrates in vacuum. For example, the slotted member and the base mayconsist (essentially) of aluminum, in view of machinability and vacuumcompatibility requirements. Other solid materials may be used forforming the slotted member and the base, and a suitable alternativeadhesive material may be used that bonds to the surfaces of the slottedmember and the base. The sealing body may be formed from liquid sealantmaterial that adheres to the one or more solid materials and fixes theslotted member to the base, when cured.

According to embodiments, the plurality of signal conductors is providedas a plurality of optical fibers, a plurality of electrical conductors,and/or a plurality of electrical conductors in a printed circuit board(PCB). Such PCB comprises a plurality of electrical conductorsintegrated on and/or embedded within one or more layers of material. ThePCB may be rigid and/or flexible. In some embodiments, the PCB comprisesa central part comprising a plurality of electrical conductors, thecentral part to be arranged within the slot of the slotted member. ThePCB may further comprise one or more distal parts, connected with thecentral portion and generally comprising one or more electricalcomponents and connectors or terminals for connecting to conductors orwiring which are external of the PCB. The central portion may beflexible or rigid. The distal portions are generally rigid, althoughthese might also be flexible.

According to a second aspect of the invention, and in accordance withthe advantages and effects discussed herein above with reference to thefirst aspect, there is provided a signal conductor path arrangementincluding signal conductors, a feedthrough device according to the firstaspect, and a sealing body. The slotted member is accommodated in thehole of the base. The signal conductors extend along each other to forma signal conductor group with a group width. The signal conductor groupis arranged with a longitudinal portion inside the slot of the slottedmember, in order to extend between the first and second surfaces of theslotted member through the feedthrough device. The sealing body coversthe first surface of the slotted member and at least the part of theslot where the signal conductor group exits the slot, to envelop thesignal conductor group and provide a hermetic barrier between first andsecond (distinct) regions, which are outside the slotted member andborder on the first and second surfaces of the slotted memberrespectively.

The sealing body may be a thermosetting material. In one embodiment, itmay comprise an epoxy based material, preferably a two-component epoxye.g. comprising a modified amine hardener. Suitable candidates may bethose that have low outgassing properties. The sealing body may also bedistinguished over elastomer-based seals by its high hardness.Preferably, the sealing body has a Shore D hardness of greater than 50.The viscosity of uncured liquid sealant material is preferablysufficiently low to allow it to enter the slot(s) and locally envelopthe signal conductor group inside this slot, but also sufficiently highto prevent the liquid sealant material from flowing through the entireslot and via the second surface out of the slotted member. In the casethat a maximum distance between an inner wall of a slot and an outersurface of a signal conductor within the group inside this slot isalways below 0.5 mm, a viscosity in a range of 20 Pa·s to 50 Pa·s may besuitable.

According to an embodiment, the signal conductor path arrangementcomprises further signal conductors, which extend alongside each otherin arrays to form further signal conductor groups with group widths. Theslotted member may include further slots, which extend along thefeedthrough direction through the slotted member and open into the firstand second surfaces to allow the signal conductor groups to pass fromthe first surface through the slotted member to the second surface. Eachslot may further open into a respective longitudinal opening along theside surface of the slotted member, and extend from the side surface upto a slot depth into the slotted member. The sealing body covers allslots to form the hermetic barrier.

The signal conductor path arrangement may thus route multiple groups ofsignal conductors, which are preferably substantially flat, via separateslots through the feedthrough device, while retaining all signalconductors in a well-defined spatial order. The signal conductor patharrangement may comprise one or more feedthrough devices.

The longitudinal openings may be provided on the same and/or on oppositeflat surface portions of the side surface of the slotted member. Amultitude of signal conductor groups is easier to insert into aplurality of slots, if the slots are located in such flat lateralsurface portions.

According to an embodiment, the signal conductors have a signalconductor diameter Øf and are arranged alongside each other into asingle-layered array, to form the signal conductor group with a groupthickness that is at least equal to the signal conductor diameter butsmaller than twice the signal conductor diameter. This applies inparticular to embodiments where the signal conductors are opticalfibers.

By arranging the signal conductors alongside into a single-layered arrayto form a flat signal conductor group, the ordering of the signalconductors, in particular optical fibers, within one group remainsuniquely defined and clearly identifiable, even after longitudinalportions of the signal conductor groups have been enclosed in theslotted member and embedded within the sealing body after completion ofthe device. A grouping of signal conductors into a single-layered arrayimplies that signal conductors, such as optical fibers, have at most twonearest neighbors within the signal conductor group. Formation of atwo-dimensional stacking of signal conductors and 2D-enclosure of a voidby the signal conductors is thus avoided. The axial centers of thesignal conductors may have varying positions in a transverse (thickness)direction, to yield a group thickness Hf that exceeds the signalconductor diameter. For cylindrical optical fibers with circular outercross-sections Øf, the group thickness Hf preferably stays within arange Øf Hf≤1.86·Øf.

According to a further embodiment, the slot has a slot width ΔYstransverse to both the feedthrough direction and the slot depth ΔZs, andthe slot width ΔYs is within a range defined by Øf<ΔYs<2·Øf, with Øf theouter diameter of the signal conductors.

By providing slots with a width ΔYs in the specified range, each flatsingle-layered group of signal conductors may be accommodated in anassociated slot, while the slot prevents signal conductors of the samegroup from crossing each other and/or from forming a multi-layeredarray. Hence, the signal conductors stay in their predetermined spatialarrangement. Preferably, the slot width ΔYs is within a rangeØf<ΔYs<1.86·Øf, or more preferably within a range Øf<ΔYs<1.5·Øf. Theslot thus prevents signal conductors within the same group from forminga staggered dual-layered group of signal conductors. This isparticularly advantageous when the signal conductors are provided asoptical fibers.

According to embodiments, the slotted member and the base of the signalconductor path arrangement consist essentially of solid materials, andthe signal conductors are coated on outer surfaces with a material thatis essentially the same as the material of the slotted member.Alternatively, the signal conductors are coated with a materialdifferent from the material of the slotted member but to which theliquid sealant material also adheres. Adherence of the sealing materialto the signal conductors, e.g., optical fibers, electrical conductors,or printed circuit board (PCB), contributes to the sealing properties ofthe feedthrough device.

The sealing body may then be formed from an adhesive-sealant materialthat is optimized for bonding to the coating on the outer surfaces ofthe signal conductors, e.g. coated optical fibers or a coated PCB, andthe slotted member. The optical fibers may for example be coated with asolid metal, such as aluminum. Such a metal (e.g. aluminum) coatingreduces outgassing of the fibers inside the vacuum chamber. The PCB, orat least a portion thereof which is to be in contact with the sealingbody, may be coated with a solid metal, such as (galvanized) copper,providing good adhesion for a sealing body of the types described above.

According to embodiments, the signal conductor group comprises a firstconnector at a first end that is located in the first region (e.g.associated with the inside of a vacuum chamber), or a second connectorat an opposite second end that is located in the second region (e.g.associated with the outside of a vacuum chamber), or connectors at bothends. Alternatively or in addition, further signal conductor groups mayinclude similar connectors at one or both ends. The connectors may begrouped to form connector panels, to improve manageability andstructural robustness of the signal conductor path arrangement. Thefirst connector and/or the second connector may for example be multipoleconnectors.

The signal conductor path arrangement may include a panel onto which theone or more feedthrough devices are mounted. Such a panel may form awall part that is sealingly attachable to and removable from a largerstructure, like a wall of a vacuum chamber. The resulting modularity ofthe signal conductor path arrangement facilitates manufacturing and/ormaintenance.

According to a third aspect, and in accordance with the advantages andeffects discussed herein above with reference to the previous aspects,there is provided a vacuum chamber. The vacuum chamber comprises atleast one wall and a signal conductor path arrangement in accordancewith the second aspect, which is provided at or in the wall. The atleast one group of signal conductors in the signal conductor patharrangement extends from a first region on one side of the wall, via thefeedthrough device through the wall, to a second region on an oppositeside of the wall.

According to a fourth aspect, and in accordance with the advantages andeffects discussed herein above with reference to the previous aspects,there is provided a target processing system, which comprises a vacuumchamber according to the third aspect. The target processing system maybe a lithography processing or exposure system, for example a chargedparticle beam lithography system or an electromagnetic beam lithographysystem.

According to an embodiment, the target processing system is configuredto generate and project beams of radiation towards a target inside thevacuum chamber. The target processing system may comprise a beamswitching module, which is arranged inside the vacuum chamber, and isconfigured to modulate and/or select beams for projection onto thetarget based on control signals. The signal conductor path arrangementmay be adapted to transmit the control signals from a control unitexternal to the vacuum chamber, via the signal conductors that extendthrough the feedthrough device, to the beam switching module.

The slotted member, and its various features and advantages, may in andof itself be considered a further aspect of the invention.

The various embodiments described above may be combined.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments will now be described, by way of example only, withreference to the accompanying schematic drawings in which correspondingreference symbols indicate corresponding parts. In the drawings, likenumerals designate like elements. Multiple instances of an element mayeach include separate letters appended to the reference number. Forexample, two instances of a particular element “20” may be labelled as“20a” and “20b”. The reference number may be used without an appendedletter (e.g. “20”) to generally refer to an unspecified instance or toall instances of that element, while the reference number will includean appended letter (e.g. “20a”) to refer to a specific instance of theelement.

FIG. 1 schematically shows a target processing system including a signalconductor path according to an embodiment;

FIG. 2 shows a perspective view of an embodiment of an optical fiberpath arrangement, including five fiber feedthrough devices;

FIGS. 3a-3b show perspective views of an optical fiber feedthroughdevice according to an embodiment;

FIGS. 4a-4b schematically show perspective views of a slotted memberfrom FIGS. 3a -3 b;

FIGS. 5a-5c schematically show perspective views of a PCB feedthroughdevice according to embodiments; and

FIG. 6 schematically shows a signal conductor group in the form of aprinted circuit board.

The figures are meant for illustrative purposes only, and do not serveas restriction of the scope or the protection as laid down by theclaims. It can further be mentioned that the figures are not necessarilydrawn to scale.

DESCRIPTION OF EMBODIMENTS

The following is a description of certain embodiments of the invention,given by way of example only and with reference to the figures. In thefigures, Cartesian coordinates will be used to describe spatialrelations for exemplary embodiments of the feedthrough device, signalconductor path arrangement, vacuum chamber, and processing system.Reference symbols X, Y, and Z are used to indicate first, second, andthird orthogonal directions, respectively, and may include distinctsubscripts to indicate directional definitions for different objects. Aplus or minus sign is used to specifically indicate a positive ornegative direction, or omitted if the sign is clear from the context orimmaterial.

It should be understood that the directional definitions and preferredorientations presented herein merely serve to elucidate geometricalrelations for specific embodiments. The concepts discussed herein arenot limited to these directional definitions and preferred orientations.Similarly, directional terms such as “top,” “bottom,” “left,” “right,”“up,” “down,” “upper,” “lower,” “proximal,” “distal” and the like, areused herein solely to indicate relative directions and are not otherwiseintended to limit the scope of the invention or claims.

The term “surface” is used herein to generally refer to atwo-dimensional parametric surface region, which may have either anentirely flat shape (i.e. a plane), a piece-wise flat shape (e.g. apolygonal surface), a curved shape (e.g. cylindrical, spherical,parabolic surface, etc.), a recessed shape (e.g. stepped or undulatedsurface), or a more complex shape. The term “plane” is used herein torefer to a flat surface defined by three non-coinciding points.

FIG. 1 schematically shows a target processing system 10 with a vacuumchamber 20 and a signal conductor path arrangement 40. Signal conductorcabling 16 is hermetically passed through a chamber wall 23, 24 thatseparates two regions 21, 22 with different ambient conditions. In thisexemplary embodiment, the target processing system 10 is a chargedparticle lithography system, which is adapted for lithographicprocessing of a semiconductor target 28 e.g. to create structures onto aresist-covered semiconductor substrate. Here, the different ambientconditions involve pressure differences.

As described above, the signal conductor cabling may comprise opticalfibers and/or electrical cabling or wiring, for example in the form ofone or more PCB's.

The target processing system 10 comprises a vacuum chamber 20, and aparticle beam projection column 30. The vacuum chamber 20 is configuredto maintain a vacuum environment in the inner region 21. This vacuumenvironment corresponds with a chamber pressure P; of 10⁻³ millibar orlower, for example a pressure range of 10⁻⁷ millibar to 10⁻⁴ millibar.The target processing system 10 comprises or is coupled to evacuationmeans, for example a vacuum pump system (not shown), which is configuredto evacuate (i.e. withdraw air and/or gas from) the vacuum chamber 20.

The target processing system 10 also comprises a control unit 12. Thiscontroller 12 may be located outside the vacuum chamber 20, for examplein a separate cabinet that is positioned on top of the vacuum chamber 20(not shown).

The projection column 30 is accommodated inside the vacuum chamber 20,and is adapted to generate, shape, and project one or more chargedparticle beams, for example electron beamlets 38, toward the target 28.The target 28 is also located inside the vacuum chamber 20 duringlithographic processing. The projection column 30 may comprise various(electron) optical elements, among which are means for forming theplurality of beamlets 38, and a beam switching module 36. The beamswitching module 36 is controllable by optical signals, to modulate andselect beamlets 38 for projection onto a surface of the target 28. Theoptical signals may be transmitted into the vacuum chamber via theoptical fiber feedthrough device as described herein.

Various components located within the vacuum chamber, including theelectron optical components, are connected to respective power supplies,located outside the vacuum chamber, via electrical conductors orcabling. Further electrical conductors or cabling provide controlsignals from a control unit, located outside the vacuum chamber, tovarious electrical components and devices located within the vacuumchamber. Still further signal conductors, including electricalconductors and/or optical fibers, may be provided for transmittingsignals to and/or from various sensors located within the vacuum chamberto the control unit. All these types of signals may be transmitted intothe vacuum chamber via the electrical feedthrough devices, in particularthe PCB feedthrough device, as described herein. For example, electroniccomponents provided in the beam switching module 36 may be poweredand/or controlled by signal transmitted via the PCB feedthrough device.

The vacuum chamber 20 is formed by multiple walls 23, 24, which aremechanically interconnected and form an impermeable material barrierbetween the chamber's inner region 21 and the region 22 outside thevacuum chamber 20. On one lateral wall 24 a, the vacuum chamber 20includes a feedthrough section 26, which comprises the signal conductorpath arrangement 40. In this exemplary embodiment, the feedthroughsection 26 of the signal conductor path arrangement 40 includes arelatively flat panel structure, with two opposite panel surfaces thatface laterally into and outwards from the vacuum chamber 20,respectively. The signal conductor path arrangement 40 is provided witha plurality of feedthrough devices 50, which are adapted for routinggroups of signal conductors, e.g. groups 60 of optical fibers 61 or aPCB 160 comprising electrical conductors 161, through the feedthroughsection 26 of lateral wall 24 a. The feedthrough devices, which will bedescribed in more detail herein below, enable transmitting the varioussignals through the vacuum boundary of the vacuum chamber whilemaintaining vacuum conditions.

These signal conductors are part of the signal conductor cabling 16,which traverses the outer region 22, and passes in a hermetically sealedmanner through the feedthrough section 26 of the lateral wall 24 a, tothe inner region 21. The cabling 16 generally includes a sequence ofinterconnected cable segments 17, 18, 19. A first cabling segment 17 islocated in the outer region 22, and is subjected to external ambientconditions (which in this example corresponds to a normal atmosphericpressure P_(o)). The second cabling segment 18 extends through the wallsection 26, and is partly located in the outer region 20, and partlylocated in the inner region 21, the latter region being associated withprocessing conditions (which in this case corresponds to the lowpressure P_(i)). The third cabling segment 19 is located entirely in theinner region 21, and extends through the vacuum chamber 20 towards thebeam switcher module 36. Signal conductor groups in the second cablingsegment 18 comprise an ordered group of first connectors 42 at a firstend that is located in the inner region 21, and an ordered group ofsecond connectors 44 at an opposite second end that is located in theouter region 22. The first and second connectors 42, 44 may for examplebe multipole connectors.

FIG. 2 schematically shows an exemplary embodiment of a signal conductorpath arrangement 40 in the target processing system 10 from FIG. 1. Inthis example, the signal conductor path arrangement 40 is formed as afiber path arrangement 40 a. However, the concept of the fiber patharrangement of FIG. 2 can analogously be applied for other types ofsignal conductor path arrangements, for example an electrical conductorpath arrangement comprising PCB feedthrough devices 150 as describedwith reference to FIGS. 5a to 5c herein below.

In the embodiment of FIG. 2, the optical fiber path arrangement 40 aincludes five fiber feedthrough devices 50 a-50 e. In other embodiments,the fiber path arrangement may include any positive integer number offeedthrough devices. In this example, the optical fiber path arrangement40 a comprises a flat panel 26 with five regions onto which the fivefiber feedthrough devices 50 are mounted in a hermetically sealedmanner. The panel 26 itself is formed as a unit that is sealinglyattachable to and removable from the lateral wall 24 a of the vacuumchamber 20, to facilitate manufacturing and/or maintenance of theoptical fiber path arrangement 40 a.

FIGS. 3a and 3b show details of a single fiber feedthrough device 50from the arrangement 40 a of FIG. 2. The fiber feedthrough device 50comprises a slotted member 52, a base 62, a plurality of fiber groups60, and a body of sealing material 71. FIG. 3a shows the feedthroughdevice 50 in largely disassembled state, wherein the slotted member 52is not inserted into the base 62. FIG. 3b shows the feedthrough device50 in an assembled state, wherein the slotted member 52 is accommodatedin the base 62, and the sealing body 71 is applied (only partly shownfor illustration purposes). Features described above with reference toFIG. 1 are also present in the arrangement shown in FIGS. 2 and 3 a-3 b.

In FIG. 2, the optical fiber path arrangement 40 a is shown from aposition corresponding to the outer region 22 i.e. outside the vacuumchamber 20. Each of these feedthrough devices 50 includes a slottedmember 52 (see FIG. 3a ), which is accommodated in a through hole 65 ofan associated base 62, and covered by a corresponding sealing body 71.Each such slotted member 52 forms a passageway for a plurality of flatfiber groups 60. The fiber groups 60 extend with longitudinal portionsalong a first direction X (also indicated as feedthrough direction)through associated slotted members 51 of corresponding feedthroughdevices 50. FIGS. 2-3 b only indicate fiber groups 60 a-60 h, which areassociated with the uppermost feedthrough device 50 a. The sealingbodies 71 cover portions of corresponding feedthrough devices 50 wherethe fiber groups 60 exit these devices 50, and locally envelop the fibergroups 60 to provide material barriers that hermetically separate theinner region 21 of the vacuum chamber 20 from the outer region 22. Inthis example, the inner region 21 is located at a side of the panel 26that faces towards a negative feedthrough direction −X, and the outerregion 22 is located at a side of the panel 26 that faces towards apositive feedthrough direction +X.

Although the embodiments of FIGS. 3a-3b are discussed with reference tosignal conductors in the form of optical fibers, the teachinganalogously applies to signal conductors in the form of electricalconductors or wires. The slotted member, the base and the sealing bodymay be analogously used for a PCB feedthrough, where a PCB is insertedinto the slots. Specific embodiments of such PCB feedthroughs areillustrated in FIGS. 5a-5c and described further below.

FIG. 3a illustrates that the slotted member 52 is formed by a body ofsolid material, which in this example consists essentially of aluminum.Along the positive and negative feedthrough directions ±X, the slottedmember 52 is delimited by the first surface 53 and the second surface54, respectively. The first and second surfaces 53, 54 are located onessentially opposite sides of the slotted member 52. Along second andthird directions Y, Z, the slotted member 52 is delimited by a sidesurface 55, 56 that extends along the entire periphery of the slottedmember 52. The side surface 55, 56 interconnects the first and secondsurfaces 53, 54.

Cross-sectional outer contours of this side surface 55, 56 in transverseYZ-planes resemble stadium shapes. A stadium is a two-dimensionalgeometric figure composed of a rectangle with semicircles at twoopposite sides, with a periphery including two linear segments thatinterconnect two semi-circular segments. The stadium-shapedcross-sections of the side surface 55, 56 may include one or more smallrecesses and/or protrusions, though.

The side surface 55, 56 of the slotted member 52 has a first taperedsurface segment 55 bordering on the second surface 54, and a secondtapered segment 56 bordering on the first surface 53. The tapered shapesimply that the (stadium-shaped) cross-sectional outer contours of eachof the surface segments 55, 56 in transverse YZ-planes are congruent,and increasing in size (first segment 55) or decreasing in size (secondsegment 56) as a function of position along the positive feedthroughdirection +X.

The slotted member 52 defines a plurality of slots 58. Each slot 58forms a substantially flat cut-out, which extends entirely through thesolid body of the slotted member 52 along the feedthrough direction X.Each group 60 of fibers is accommodated within an associated slot 58.

The base 62 is formed by a distinct body, which is also formed of asolid material. In this example, the base 62 also consists essentiallyof aluminum. The base 62 defines a first outer surface 63 and a secondouter surface 64 on essentially opposite sides, viewed along thefeedthrough direction X. In this example, the first and second outersurfaces 63, 64 are flat and substantially parallel. A distance betweenthe first and second surfaces 63, 64 corresponds to a thickness ΔXb ofthe base 62, which in this example is about 20 millimeters. In use, thebase 62 is rigidly fixed to the panel 26 of FIG. 2 and sealed withrespect to this panel e.g. by means of an O-ring (not shown) provided onthe second outer surface 64.

The base 62 defines a central through hole 65, which extends entirelythrough the base 62. The through hole 65 opens into the first outersurface 63 at one end, and into the second outer surface 64 at theopposite end. Along the second and third directions Y, Z, the throughhole 65 is delimited by an inner surface 66 of the base 62. This innersurface 66 also has a tapered stadium shape. This stadium-shaped innersurface 66 is predominantly congruent with the first side surfacesegment 55 of the slotted member 52. In this way, the slotted member 52can be arranged inside the aperture 65 of the base 62 in a form-fittingmanner.

FIG. 3b shows the slotted member 52 arranged in a form-fitting mannerinside the through hole 65. In this assembled state, the first sidesurface segment 55 of the slotted member 52 and the inner surface 66 ofthe base 62 abut, and the inner surface 66 covers the parts of thelongitudinal openings 59 that are located at the first side surfacesegment 55.

In the assembled state of the embodiment shown in FIG. 3b , the firstsurface 53 of the slotted member 52 is receded with respect to the firstsurface 63 of the base 62. The first surface 53 of the slotted member 52and part of the inner surface 66 of the base 62 jointly define areceptacle 69. In this example, the receptacle 69 is predominantlystadium-shaped.

In order to form the sealing body 71, the receptacle 69 is initiallyfilled with a sealant material. In this example, the receptacle 69 isfilled up to the level of the first surface 63. After curing, thissealant material forms the sealing body 71. This sealing body 71 coversthe first surface 53 and the second surface segment 56 of the slottedmember 52, as well as the parts of the slots 58 where the fiber groups60 exit the slots 58, to envelop the fiber groups 60. In FIG. 3b , onlypart of the sealing body 71 is shown for illustrative purposes. Itshould be understood that, in this example, the completed sealing body71 occupies the entire space of the receptacle 69, to cover all slots 58and envelop all fiber groups 60 in a sealing manner.

FIGS. 4a-4b schematically show more details of the slotted member 52from FIGS. 3a-3b . Similar or analogous details apply for the slottedmember 152 from FIG. 5a-5c below. Each slot 58 in the slotted member 52extends entirely through the solid body of the slotted member 52 alongthe feedthrough direction X, between the first surface 53 and the secondsurface 54. A distance between the first surface 53 and second surface54 of the slotted member 52 corresponds with a thickness ΔXm of theslotted member 52. In this example, the slotted member thickness ΔXmabout 17 millimeters. The length ΔXs of the slot 58 in the feedthroughdirection X is identical to the thickness ΔXm of the slotted member 52.The thickness ΔXb of the base 62 along the feedthrough direction X issufficient to allow the parts of the longitudinal openings 59 that arelocated at the first side surface segment 55 to be covered by the innersurface 66.

FIG. 4a illustrates that the slots 58 also open into longitudinalopenings 59, which extend along the entire side surface 55, 56 of theslotted member 52, thus intersecting both the first tapered side surfacesegment 55 and the second tapered side surface segment 56. Theselongitudinal openings 59 are provided on both linear portions 57 a, 57 b(see FIG. 4b ) of the side surface 55, 56 of the slotted member 52.

FIG. 4b illustrates interrelations between the slots 58 and the fibergroups 60 in more detail. The individual fibers 61 in one fiber group 60are laterally arranged in a linear array. In this example, each fibergroup 60 is formed by at least twenty fibers 61, which extend alongsideeach other in a single-layered array of co-directional and abuttingfibers 61. The fibers 61 locally extend in a mutually parallel manner,so that the local tangent vectors of the fibers 61 point in the samedirection (here along the feedthrough direction X). Each individualfiber 61 has only two directly neighboring fibers 61. The exception tothis are the first fiber 61 a and the last fiber 61 j, which arearranged at the two sides of the fiber group 60, and which have only onedirectly neighboring fiber (i.e. the second fiber 61 b and thepenultimate fiber 61 i respectively). The optical fibers 61 haveessentially identical fiber diameters Øf. The fiber diameter Øf may bein a range of about 0.125 millimeters to 0.25 millimeters. In thisexample, the fiber diameter Øf has a value of about 0.175 millimeters.As a result, a thickness Hf of the fiber group 60 along the seconddirection Y is substantially equal to the fiber diameter Øf, and a widthWf of the fiber group 60 along the third direction Z is at least twentytimes the fiber diameter Øf.

Each slot 58 extends perpendicularly into the slotted member 52, herealong the (positive/negative) third direction Z (also indicated as thedepth direction Z). The slot 58 has a depth ΔZs in this depth directionZ, which is at least equal to the group width Wf (i.e. at least twentytimes the fiber diameter Øf in this example). The slot 58 has a widthΔYs in the second direction Y, which complies with Øf<ΔYs<2·Øf. In thisexample, the slot width ΔYs is only marginally larger than the fiberdiameter Øf, and has a value of about 0.25 millimeters. Whenaccommodated inside the corresponding slot 58, the fibers 61 will notcross each other, at least along the entire extent of the slot 58.

The optical fibers 61 are coated on outer surfaces with aluminum, toreduce outgassing effects inside the vacuum chamber 20. This aluminumcoating also facilitates adhesion of the sealing body 71 to the slottedmember 52, the base 62, and the optical fibers 61.

In alternative embodiments, some or all of the fibers in one fiber groupdo not directly abut in a lateral direction (here, in the depthdirection Z). Instead, some or all pairs of directly neighboring fibersmay extend alongside each other while defining a small space in between.Such spaces allow a larger portion of the transverse cross-sectionalperipheries of corresponding fibers to be enveloped by the sealing body(e.g. cured sealant material). In such embodiments, a width Wf of thefiber group will exceed the product of the number of fibers in the groupand the fiber diameter Øf.

FIGS. 5a and 5b show details of PCB feedthrough devices, such as the PCBfeedthrough device 150 illustrated in FIG. 5c in an assembled state.FIGS. 5a and 5b show a slotted member 152 a, 152 b, provided with slots159, 159 a, 159 b into each of which a PCB 160, 160 a-160 d is inserted.In FIGS. 5a and 5b the slotted member 152 a, 152 b is not inserted intothe base 162.

The slotted members 152, 152 a, 152 b, referred to herein below by 152,of FIGS. 5a-5c are analogous to the slotted member 52 of FIGS. 3a and 3b. The slotted members 152 are formed by a body of solid material, andfor example consist essentially of aluminum. Along the positive andnegative feedthrough directions ±X, the slotted member 152 is delimitedby the first surface 153 and the second surface 154, respectively. Thefirst and second surfaces 153, 154 are located on essentially oppositesides of the slotted member 152. Along second and third directions Y, Z,the slotted member 152 is delimited by a side surface 155, 156 thatextends along the entire periphery of the slotted member. The sidesurface 155, 156 interconnects the first and second surfaces 153, 154.

Cross-sectional outer contours of this side surface 155, 156 intransverse YZ-planes resemble stadium shapes. A stadium is atwo-dimensional geometric figure composed of a rectangle withsemicircles at two opposite sides, with a periphery including two linearsegments that interconnect two semi-circular segments. Thestadium-shaped cross-sections of the side surface 155, 156 may includeone or more small recesses and/or protrusions, though.

The side surface 155, 156 of the slotted member 152 has a first taperedsurface segment 155 bordering on the second surface 154, and a secondtapered segment 156 bordering on the first surface 153. The taperedshapes imply that the (stadium-shaped) cross-sectional outer contours ofeach of the surface segments 155, 156 in transverse YZ-planes arecongruent, and increasing in size (first segment 155) or decreasing insize (second segment 156) as a function of position along the positivefeedthrough direction +X.

The slotted member 152 defines one or more slots 158. The slotted member152 a of FIG. 5a is provided with one slot 158, and hence feeds throughone PCB 160. The slotted member 159 b of FIG. 5b comprises four slots158, enabling feeding through four PCB's 160-160 d. The number of slots158 provided in the slotted member, as well as their arrangement, i.e.position and orientation in the slotted member, and the specificdimensions of the slotted member 152, may be selected based on thespecific application, and the arrangements of PCB's and/or electricalconnections which are to be arranged in the feedthrough.

In the illustrated embodiment, the slots 158 in the slotted member 152for the PCB feedthrough device are directed along the Y direction, i.e.substantially perpendicular to the direction of the slots 58 in theslotted member 52 of the optical fiber feedthrough device 50. However,it should be noted that the slots 158 for the PCB feedthrough device mayalternatively be oriented along the Z direction, in the same directionas the slots 58 for the optical fiber feedthrough device, and viceversa. Furthermore, the slotted member may be configured with one ormore slots 158 for accommodating a PCB, and one or more slots 58 foraccommodating optical fiber groups.

Each slot 158 forms a substantially flat cut-out, which extends entirelythrough the solid body of the slotted member 152 along the feedthroughdirection X. Each PCB 160 is accommodated within an associated slot 158.The width ΔZsa of the slot 158 slightly exceeds the thickness of the PCB160 in the area thereof passing through the slot 158. For example, thePCB may be 300 μm thick, whereby the slot has a width of 400-500 μm. Thedepth ΔYsa of the slot preferably exceeds the width of the PCB 160 inthe area thereof passing through the slot 158.

Analogous to the illustration in FIG. 4a , each slot 158 in the slottedmember 152 extends entirely through the solid body of the slotted member152 along the feedthrough direction X, between the first surface 153 andthe second surface 154. A distance between the first surface 153 andsecond surface 154 of the slotted member 152 corresponds with athickness ΔXm of the slotted member 152. The length ΔXs of the slot 158in the feedthrough direction X is identical to the thickness ΔXm of theslotted member 152. The thickness ΔXb of the base 162 along thefeedthrough direction X is sufficient to allow the parts of thelongitudinal openings 159 that are located at the first side surfacesegment 155 to be covered by the inner surface.

The slots 158 also open into longitudinal openings 159, which extendalong the entire side surface 155, 156 of the slotted member 152, thusintersecting both the first tapered side surface segment 155 and thesecond tapered side surface segment 156.

FIG. 5c shows a PCB feedthrough device 150, which may be comprised inthe signal conductor path arrangement 40 of FIG. 1. The PCB feedthroughdevice 150 comprises a slotted member 152, a base 162, a PCB 160comprising a plurality of electrical conductors (not illustrated in FIG.5a-5c ), and a body of sealing material 171. FIG. 5c shows thefeedthrough device 150 in an assembled state, wherein the slotted member152 is accommodated in the base 162, and the sealing body 171 is applied(only partly shown for illustration purposes). Features described abovewith reference to FIG. 1 are also present in the arrangement shown inFIGS. 5a-5c . The slotted member 152 has been described with referenceto FIG. 5a , 5 b.

In particular, the feedthrough device of FIG. 5c comprises a slottedmember and PCB as illustrated in FIG. 5a . Analogously, the slottedmember 152 b and PCB's 160 a-c of FIG. 5c can be arranged in the base162 to form a PCB feedthrough device.

The base 162, illustrated in FIG. 5c , is similar to the base 62 ofFIGS. 3a, 3b . The base 162 is formed by a distinct body, which is alsoformed of a solid material, for example, essentially aluminum. The base162 defines a first outer surface 163 and a second outer surface(similar to the second outer surface 64) on essentially opposite sides,viewed along the feedthrough direction X. In this example, the first andsecond outer surfaces are flat and substantially parallel. A distancebetween the first and second surfaces corresponds to a thickness ΔXb ofthe base 162, which in this example is about 20 millimeters. In use in asignal conductor path arrangement according to the principle illustratedin FIG. 2, the base 162 is rigidly fixed to the panel 26 and sealed withrespect to this panel e.g. by means of an O-ring (not shown) provided onthe second outer surface.

The base 162 defines a central through hole (similar to the through hole65), which extends entirely through the base 162. The through hole opensinto the first outer surface 163 at one end, and into the second outersurface at the opposite end. Along the second and third directions Y, Z,the through hole is delimited by an inner surface (similar to the innersurface 66) of the base 162. This inner surface also has a taperedstadium shape. This stadium-shaped inner surface is predominantlycongruent with the first side surface segment 155 of the slotted member152. In this way, the slotted member 152 can be arranged inside thethrough hole of the base 162 in a form-fitting manner.

FIG. 5c shows the slotted member 152 arranged in a form-fitting mannerinside the through hole 65. In this assembled state, the first sidesurface segment 155 of the slotted member 152 and the inner surface ofthe base 162 abut, and the inner surface covers the parts of thelongitudinal openings 159 that are located at the first side surfacesegment 155.

In the embodiment of FIG. 5c the first surface 153 of the slotted member152 is receded with respect to the first surface 163 of the base 162,whereby the first surface 153 and part of the inner surface jointlydefine a receptacle 169.

In order to form the sealing body 171, the receptacle 169 is initiallyfilled with a sealant material. In this example, the receptacle 169 isfilled up to the level of the first surface 163. After curing, thissealant material forms the sealing body 171. This sealing body 171covers the first surface 153 and the second surface segment 156 of theslotted member 152, as well as the parts of the slots 158 where thePCB's 160 exit the slots 158, to envelop the PCB 160. In FIG. 5c , onlypart of the sealing body 171 is shown for illustrative purposes. Itshould be understood that, in this example, the completed sealing body171 occupies the entire space of the receptacle 169, to cover all slots158 and envelop all PCB's 160 in a sealing manner.

The PCB feedthrough devices as described herein, for example the PCBfeedthrough 150, may be incorporated in a signal conductor patharrangement, for example forming a PCB path arrangement, analogous tothe optical fiber path arrangement 40 a of FIG. 2.

FIGS. 6a and 6b schematically illustrate an embodiment of a PCB 160 ofthe PCB feedthrough device 150. The PCB 160 comprises a central portion180, whose middle portion 180 a is configured to be inserted into theslot 158 and to be sealed by the sealing body 171. To this end, theouter surfaces of the middle portion 180 a are provided with a materialproviding good adhesion with the sealing body, such as to form ahermetic seal. This can for example be realized by a copper coating, orany other material to which the sealing body adhere. The PCB 160comprises a first part 181, arranged on the vacuum side of thefeedthrough device, and a second part 182, arranged on the ambient sideof the feedthrough device. The first and second parts 181, 182 areconnected to the central part 180 via distal portions 180 b, 180 cthereof. The distal portions 180 b, 180 c are not in contact with thesealing body and hence do not necessarily be provided with a materialhaving good adhesion therewith, although they may be provided with suchmaterial. The different parts of the PCB 160, in particular the firstpart 181 and the central part 180, are further configured to be vacuumcompatible, having low outgassing properties.

The central part 180 of the PCB may be formed by a flexible PCB, or by arigid PCB, depending e.g. on the desired arrangement, e.g. orientation,of the first and/or second parts 181, 182 in relation to the centralpart 180. The first and second parts 181, 182 are generally rigid.

As illustrated in FIG. 6b , the first and second parts 181, 182 comprisefirst connectors 142 a-142 d and second connectors 144 a-144 d,respectively. The first connectors 142 are configured for connection tocables or wiring located within the vacuum chamber, e.g. to the thirdcable segment 19 of FIG. 1. Analogously, the second connectors 144 areconfigured for connection to cables or wiring located outside the vacuumchamber, e.g. to the first cable segment 17 of FIG. 1. Furthermore, thefirst and second parts 181, 182 may comprise various electroniccomponents (not illustrated). Electrical conductors 161 a-161 d, passingthrough the central part 180, connect the first and second conductors142 a-d, 144 a-d. For ease of illustration, only four conductors areshown in FIG. 6b , although the number of conductors may in general bemuch larger. Furthermore, in FIG. 6b only one layer of conductors isshown. However, the PCB 160 may comprise a plurality of layers ofconductors. Hence, the PCB provides an ordered arrangement of electricalconductors.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. It willbe apparent to the person skilled in the art that alternative andequivalent embodiments of the invention can be conceived and reduced topractice. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

Those skilled in the art and informed by the teachings herein willrealize that the invention is applicable for feeding through any numberof signal conductor groups comprising multiple signal conductors, suchas optical fibers and/or electrical conductors, for example arranged ina PCB. Any number of signal conductor path arrangements may be used, andeach arrangement may include any number of feedthrough devices.

The proposed feedthrough device and/or signal conductor path arrangementmay be employed in various types of vacuum chambers and/or targetprocessing systems. The target processing system may for example be acharged particle beamlet lithography system, an electromagnetic beamlithography system, or another type of processing system that requires ahermetic feedthrough of signal conductors between regions with differentambient conditions.

Apart from the above, it will be appreciated that the cross-sectionalshapes of the side surface of the slotted member and the inner surfaceof the base of a feedthrough device do need to be shaped according to astadium. Instead, other shapes may be possible, for example roundedrectangular, elliptic, circular, polygonal, or other cross-sectionalshapes.

LIST OF REFERENCE SYMBOLS

-   10 target processing system (e.g. lithography system)-   12 system controller-   14 optical signal generators-   16 signal conductor cabling-   16 first cable segment (external)-   17 second cable segment (intermediate transition)-   18 third cable segment (internal)-   19 vacuum chamber-   21 first region (e.g. vacuum chamber region)-   22 second region (e.g. outer region)-   23 upper chamber wall-   24 lateral chamber wall-   26 feedthrough wall section-   28 target-   30 particle beam column-   32 particle beam source (e.g. electron beam source)-   34 particle beam collimator-   36 beamlet switcher module-   37 blanker controller-   38 beamlet-   40 signal conductor path arrangement-   42 first connector (e.g. internal connector)-   44 second connector (e.g. external connector)-   50 fiber feedthrough device-   52 slotted member-   53 first surface-   54 second surface-   55 first side surface segment-   56 second side surface segment-   57 flat surface portion-   58 slot-   59 longitudinal opening-   60 flat fiber group-   61 optical fiber-   62 base-   63 first surface-   64 second surface-   65 through hole (for slotted member)-   66 inner surface-   67 coupling aperture (e.g. lateral through hole)-   68 mechanical coupling (e.g. bolt and nut)-   69 receptacle-   70 peripheral recess-   71 sealing body-   72 main seal portion-   73 flange seal portion-   142 first connectors (of PCB)-   144 second connectors (of PCB)-   150 PCB feedthrough device-   152 slotted member (of PCB feedthrough device)-   153 first surface (of PCB feedthrough device)-   154 second surface (of PCB feedthrough device)-   155 first side surface segment (of PCB feedthrough device)-   156 second side surface segment (of PCB feedthrough device)-   158 slot (of PCB feedthrough device)-   159 longitudinal opening (of PCB feedthrough device)-   160 printed circuit board (PCB)-   161 electrical conductors in PCB-   162 base (of PCB feedthrough device)-   163 first outer surface-   169 receptacle (of PCB feedthrough device)-   170 peripheral recess (of PCB feedthrough device)-   171 sealing body (of PCB feedthrough device)-   180 central part (of PCB)-   181 first part (of PCB)-   182 second part (of PCB)-   A1 insertion axis-   X first direction (feedthrough direction)-   Y second direction (transversal direction)-   Z third direction (e.g. depth direction)-   ΔXm slotted member thickness-   ΔXb base thickness-   ΔXs slot length-   ΔYs slot width-   ΔZs slot depth-   ΔYsa slot depth (PCB feedthrough embodiment)-   ΔZsa slot width (PCB feedthrough embodiment)-   Wf fiber group width-   Hf fiber group thickness-   Øf fiber diameter

1-23. (canceled)
 24. A feedthrough device for forming a hermetic sealaround a plurality of signal conductors, the signal conductors extendingalongside each other to form a signal conductor group with a groupwidth, wherein the feedthrough device comprises: a slotted member,defined by a first surface, a second surface, and a side surface, thefirst and second surfaces facing opposite each other in a feedthroughdirection (X) and the side surface configured to interconnect the firstand second surfaces, wherein the slotted member comprises at least oneslot extending along the feedthrough direction through the slottedmember and defining a passage for the signal conductor group to passthrough the slotted member, wherein the slot comprises an opening alongthe side surface and is configured to extend from the side surface intothe slotted member in a direction transverse to the feedthroughdirection; and a base with a through hole configured to extend throughthe base in the feedthrough direction between openings defined in outersurfaces of the base, wherein the through hole is adapted to accommodatethe slotted member, wherein the base comprises an inner surface definingthe through hole and extending between the openings and the innersurface is configured to cover at least part of the side surface and atleast part of the opening of the slot.
 25. The feedthrough deviceaccording to claim 24, wherein the passage is defined by the slot forthe signal conductor group to pass through the slotted member betweenthe first and second surfaces.
 26. The feedthrough device according toclaim 24, wherein a depth of the slot in the direction transverse to thefeedthrough direction is equal to or larger than the group width. 27.The feedthrough device according to claim 24, wherein the first surfaceof the slotted member is recessed along the feedthrough direction (X)relative to a surface of the base directly around the through hole, whenthe slotted member is accommodated in the through hole, so that at leastthe first surface of the slotted member and the inner surface of thebase form a receptacle in which a sealing body can be accommodated. 28.The feedthrough device according to claim 24, wherein the side surfaceof the slotted member has a cross-sectional shape that resembles astadium or a rounded rectangle, and wherein the inner surface of thebase around the though hole has cross-sectional shape adapted toaccommodate the slotted member in a form-fitting manner.
 29. Thefeedthrough device according to claim 24, wherein the side surface ofthe slotted member defines a flat surface portion that extends in atranslationally symmetric manner along a direction (Y) perpendicular tothe feedthrough direction (X), wherein the opening of the slot islocated at the flat surface portion, and wherein the at least one slotextends along the direction transverse to the feedthrough direction andperpendicular to the flat surface portion into the slotted member. 30.The feedthrough device according to claim 24, wherein the side surfaceof the slotted member defines a first side surface segment that isinwardly tapered towards an axis (A1) along the feedthrough direction,and wherein the inner surface of the base is inwardly tapered congruentto the first side surface segment.
 31. The feedthrough device accordingto claim 30, wherein the side surface of the slotted member includes asecond outer surface segment that is inwardly tapered, filleted, orchamfered towards the axis (A1) along the feedthrough direction (X) butoppositely with respect to the first side surface segment, and/orwherein the inner surface of the base includes an inner surface segmentthat is outwardly tapered, filleted, or chamfered away from the axis,such that the second side surface segment and/or inner surface segmentdefine an inwards peripheral recess directly bordering on the opening inthe slotted member, the recess configured to accommodate a portion ofthe sealing body.
 32. The feedthrough device according to claim 24,wherein the plurality of signal conductors is provided as a plurality ofoptical fibers, a plurality of electrical conductors, and/or asconductors in a printed circuit board.
 33. A signal conductor patharrangement, comprising: a feedthrough device with a slotted member anda base according to claim 24, wherein the slotted member is accommodatedin the through hole of the base; and a plurality of signal conductors,which extend alongside each other to form a signal conductor group witha group width (Wf), wherein the signal conductor group is arranged witha longitudinal portion inside a slot of the slotted member, to extend ina feedthrough direction (X) through the feedthrough device.
 34. Thesignal conductor path arrangement according to claim 33, furthercomprising: a sealing body covering the first surface of the slottedmember and at least the part of the slot where the signal conductorgroup exits the slot, to envelop the signal conductor group and providea hermetic barrier between first and second regions that are outside theslotted member and border on the first and second surfaces of theslotted member respectively.
 35. The signal conductor path arrangementaccording to claim 33, wherein the signal conductor group is arranged toextend in the feedthrough direction between the first and secondsurfaces of the slotted member through the feedthrough device.
 36. Thesignal conductor path arrangement according to claim 34, furthercomprising signal conductors, which extend alongside each other inarrays to form further signal conductor groups with group widths (Wfi),wherein the slotted member includes further slots, which extend alongthe feedthrough direction through the slotted member and define apassage for the signal conductor groups to pass through the slottedmember; wherein each further slot comprises an opening along the sidesurface and is configured to extend from the side surface into theslotted member in a direction transverse to the feedthrough direction,and wherein the opening is provided on the same and/or on opposite flatsurface portions of the side surface of the slotted member, and thesealing body covers all slots to form the hermetic barrier.
 37. Thesignal conductor path arrangement according to claim 34, wherein thebase comprises an inner surface defining the through hole configured toaccommodate the slotted member, and the inner surface of the base isconfigured to cover at least part of the side surface and at least ofthe opening of the slot.
 38. The signal conductor path arrangementaccording to claim 37, wherein the first surface of the slotted memberis recessed along the feedthrough direction (X) relative to a surface ofthe base directly around the through hole, so that at least the firstsurface of the slotted member and the inner surface of the base form areceptacle in which the sealing body is accommodated.
 39. The signalconductor path arrangement according to claim 37, wherein the sidesurface of the slotted member defines a first side surface segment thatis inwardly tapered towards an axis along the feedthrough direction, andwherein the inner surface of the base is inwardly tapered congruent tothe first side surface segment.
 40. The signal conductor patharrangement according to claim 33, wherein the signal conductors have asignal conductor diameter Øf and are arranged alongside each other intoa single-layered array, to form the signal conductor group with a groupthickness (Hf) that is at least equal to the signal conductor diameterbut smaller than twice the signal conductor diameter.
 41. The signalconductor path arrangement according to claim 34, wherein the slottedmember and the base form rigid bodies comprising one or more solidmaterials, wherein the sealing body is formed from liquid sealantmaterial that adheres to the one or more solid materials and fixes theslotted member to the base when cured.
 42. The signal conductor patharrangement according to claim 33, wherein the signal conductor groupand/or further signal conductor groups comprise a first connector at afirst end that is located in the first region, and/or comprise a secondconnector at an opposite second end that is located in the secondregion.
 43. A slotted member for a feedthrough device for forming ahermetic seal around a plurality of signal conductors, or for a signalconductor path arrangement having the feedthrough device, the slottedmember comprising: a first, a second, and a side surfaces that definethe slotted member, wherein the first and second surfaces face oppositeeach other in a feedthrough direction (X) and the side surface isconfigured to interconnect the first and second surfaces, wherein theslotted member comprises at least one slot extending along thefeedthrough direction through the slotted member and defining a passagefor a signal conductor group to pass through the slotted member, whereinthe slot comprises an opening along the side surface and is configuredto extend from the side surface in a direction transverse to thefeedthrough direction.